Method for treating ore concentrates



United States Patent 0,

Stanley, Tahawus, N; Y., assiguor to National Lead Company,.New York, N. Y., a corporation of New Jersey Application September 5, 1952, SerialNo. 308,151

. 6 Claims. (Cl. 23-117 No Drawing.

This invention relates to treatment of ore concentrates. More specifically, it relates to treatment of ore concentrates which have been prepared by flotation methods. t

.In the preparation of ore. materials for processing, it is usually necessary to remove gangue and other foreign matter from the ore as it is received from the mine before processing into various products of manufacture. It is particularly desirable to remove such materials from titaniferous iron ores in order to produce useful titanium iron concentrates. These concentrates are used in large tonnages as raw material for the manufacture of various titanium compounds, including titanium tetrachloride and titanium dioxide. During the processing of the concentrate into titanium dioxide, particularly for pigment products, digestion in sulfuric acid is often employed.

Many methods have been utilized for removing the gangue and other foreign matter from the ore to produce ore concentrates. These methods include magnetic separation, wet and dry classifiers, and flotation separation. The present invention relates particularly to the ore concentrates, particularly those of titaniferous materials which have been treated with flotation agents to remove the extraneous materialsfrom titaniferous iron ore.

Flotation methods often utilize organic compounds as the flotation agents, particularly oils and organic acids. Among the organic compounds which are often used as flotation agents for preparation of titanium concentrates are fuel oil and oleic acid. It has been found that when such organic compounds are employed that such compounds apparently remain with the flotation concentrate and cannot be removed by normal procedures such as washing. Therefore the organic agents used .in flotation concentration procedures for titanium ores are present in the concentrate and also are present in a subsequent sulfuric acid digestion step.

When titanium concentrates. which have been treated with such flotation. agents are utilized as a raw material for the production of titanium dioxide pigmets, difliculties in operation are encountered, particularly in large scale operation, in the digestion step. Normally the digestion step, that is, dissolving the titanium concentrate in hot sulfuric acid is a rapid and active reaction. This rapid reaction, however, may be controlled and held in check in large scale operations by applying suitable digestion equipment and operational technique well known in the art. However, when a titaniferous iron concentrate which has been treated with flotation agents is reacted with concentrated sulfuric acid, the reaction becomes extremely violent and sometimes approaches explosive magnitude, which is very diflicult if notsometimes impossible to control.

Many methods have been tried to alter the sulfuric digestion procedure when processing a titanium concentrate containing a flotation agent, to overcome the excessive violence of the reaction but none has been successful. It is desirabletherefore to provide a method for treating a t1tan1um concentrate contamlng an organic flotation agent in a manner which will permit the titanium 2,724,637 1 Patented Nov.- 22, 1955 ICC . r 2 concentrate to be digested in concentrated sulfuric acid in a normal manner.

An object ofthis invention therefore is to provide a method for rendering amenable to digestion in concentrated sulfuric acid a titaniferous iron concentrate containing organic flotation agents. Another object is to provide a method for treating a titanium concentrate in a manner which will overcome the violent and uncontrollable digestion reaction in concentrated sulfuric acid. A still further object is to provide an economical method for treatment of a titaniferous material containing an organic flotation agent which will permit a normal digestion procedure to be obtained without affecting the digestion efficiencies. These and other objects will become apparent from the following more complete description of the instant invention.

Broadly this invention contemplates treating atitaniferous flotation concentrate containing an organic flotation agent which comprises contacting said flotation concentrate with an aqueous solution containing a soluble in organic metaphosphate and removing said flotation concentrate from said solution. It has been found that if the flotation concentrate is treated with an aqueous solution of an inorganic metaphosphate the concentrate may be digested in concentrated sulfuric acid in a normal manner. The digestion reaction will proceed in a rapid and active manner but will not produce a violent and uncontrollable digestion reaction. It is believed that the organic flotation agent which is present in the flotation concentrate is either removed or rendered inactive during the/treatment process. In any event the flotation agent during such treatment is rendered incapable of detrimentally affecting the digestion procedure and for all practical purposes may be considered as being substantially removed by such a treatment.

The amounts of flotation agent present in the flotation concentrate are extremelysmall. Normally from 1 to 5 lbs. of organic flotation agents are employed per ton of ore in flotation methods. The amount present in the flotation concentrate is somewhat lower than the amount used in the ore slurry employed in the flotation process but usually most of the organic agents remain with the flotation concentrate. It is diflicult to determine the precise percentages of the organic flotation agents present in the flotation concentrate by analytical methods because of the,

small percentages used and therefore it is extremely diflicult to determine exactly to what extent the flotation agents may be removed during the treatment process.

According to the instant invention it has been'found that the amounts of inorganic metaphosphate used in the treatment process may vary widely. It is particularly desirable to employ from 0.5 lbs. to 2.0 lbs. of inorganic metaphosphate per ton of titanium concentrate employed. Using amounts of phosphate which fall within this range efiectively removes or renders inactive the flotation agents. Any water soluble inorganic metaphosphatemay be employed in carrying out the process of the instantinvention. Among those which are particularly desirable to employ for both effectiveness and economy are sodium metaphosphate, sodium hexametaphosphate, and, potassium metaphosphate.

In carrying out the process of this invention it has been found particularly desirable to form a slurry of the flotation concentrate by adding the latter to water with agitation. The slurry is then adjusted with acid, preferablysulfuric acid, to obtain a pH from about 1.0 to 3.5 andthe water soluble metaphosphate is then added. For most efficient results it has been found that preferably the treatment process should be carried out at a pH of from about 1.5 to 2.5. The treated concentrate is then removed by filtration and is ready for digestion in concentrated sulfuric acid. This treatment process may be carried out at Substantially any temperature but preferably at room temperature.

In order to more clearly illustrate the process of the instant invention the following examples are presented.

Example I Aytitaniferous flotation concentrate which has been prepared by treating a ton of titaniferous iron ore with 1.5 lbs. of fuel oil, and 1.0 lbs. of oleic acid in a flotation system had the following analysis:

F Per cent IfeQ 39.1 91 1 I TiQ'z m.-.- 45.9 Other matter r. 12.1 Flotation agent (oleic acid-g-fuel oil) 0.2

100 parts of this concentrate were added with agitation to an aqueous solution containing .05 part of sodium hexamet'aphosphate. The treatment process was carried out for 10 minutes. The concentrate after such treatment was removed by filtration and after drying had the following analysis:

Per cent FeO 39.5 F630: 2.8 TiOz 46.5 Other matter 11.2

Another portion of the titaniferous flotation concentrate described in Example 1 was admixed with an aqueous solution of sodium metaphosphate in the manner described in Example 1. The treated ore had the following analysis:

v Per cent eo m 39.3 FeaOs a 2.8 Ti'oz 46.3 Other matter 11.6

Again substantially all 'of the organic flotation agents present in the concentrate had been removed. The dried concentrate was digested in concentrated sulfuric acid according to the procedure described in Example 1 and a normal rapid and active action was obtained. Again 96% of the titanium values were converted to soluble sulfate during the digestion step.

Example 3 Another portion of the titaniferous flotation concentrate described in Example 1 was treated with potassium metaphosphate and the results were substantially the same as that described in Example 1.

procedure was used with equal success to remove other organic flotation agents such as pine oil, tall oil, and other fatty acids and soaps.

in order to show that flotation concentrates containing organic flotation agents cannot be digested directly in concentrated sulfuric acid without extreme violence, the following digestion was carried out for comparison A portion of the flotation concentrate described in Example 1 containing the flotation agents which was not treated according to the process of the instant invention was digested directly in concentrated sulfuric acid. Immediately upon admixture with hot sulfuric acid, copious fuming took place and substantially all of the reaction mass foamed and spilled over the top of the reaction vessel. The reaction was extremely violent and could not be held in the reaction vessel. In fact very little of the reaction mass remained in the vessel.

In spite of the small percentage of flotation agent which is present in the titaniferous flotation concentrate, a sulfuric acid digestion step is substantially impossible to control unless steps are taken to render the flotation agent inactive before such digestion step.

From the above description and by the examples shown, it has clearly been shown that a titaniferous flotation concentrate containing an organic flotation agent when treated according to the process of the instant invention produces a product which may be subsequently digested in sulfuric acid in a normal manner.

it has further been shown that the flotation agent contained in the flotation concentrate may be either removed substantially or rendered inactive by the treatment process of the instant invention and that after such treatment the concentrate may be digested in concentrated sulfuric acid without extreme violence and explosive characteristics of the digestion reaction. The treatment process is simple and inexpensive to employ.

While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other modifications and variations may be employed within the scope of the following claims.

I claim:

1. Method for rendering amenable to digestion in concentrated sulfuric acid a titaniferous iron concentrate containing an organic flotation agent which comprises treating said concentrate with an aqueous solution of an inorganic metaphosphate at pH of 1.0 to 3.5 and removing the treated concentrate from said solution prior to digestion of said concentrate, said flotation agent and said metaphosphate being retained in said solution and thereby separated from said treated concentrate.

2. Method according to claim 1 in which saidconcentrate is treated with an aqueous solution of an inorganic metaphosphate at pH of 1.5 to 2.5.

3. Process according to claim 1 in which the inorganic metaphosphate is present in said solution in amounts: from 0.5 lb. to 2 lbs. per ton of ore concentrate employed.

4. Method according to claim 1 in which the inorganic metaphosphate is sodium metaphosphate.

5. Method according to claim 1 in which the inorganic metaphosphate is sodium hcxametaphosphate.

6. Method according to claim 1 in which the inorganic metaphosphate is potassium metaphosphate.

OTHER REFERENCES MacMurray: 'Froth Flotation of a North Carolina Ilrnenite Ore pages 337-342, vol. 173, Transactions of American Institute of Mining and Metallurgical Engine'ers, A. I. M. E., New York city, 1948.

Barksdale: Titanium, Ronald Press, New York, 1949, Pp. 129-133.

Taggart: Handbook of Mineral Dressing, sec. 12, pp. 12-419, 12-120, 12-34, John Wiley and Sons, New York, 1945. 

1. METHOD FOR RENDERING AMENABLE TO DIGESTION IN CONCENTRATED SULFURIC ACID A TITANIFEROUS IRON CONCENTRATE CONTAINING AN ORGANIC FLOTATION AGENT WHICH COMPRISES TREATING SAID CONCENTRATE WITH AN AQUEOUS SOLUTION OF AN INORGANIC METAPHOSPHATE AT PH OF 1.0 TO 3.5 AND REMOVING THE TREATED CONCENTRATED, FROM SAID SOLUTION PRIOR TO DIGESTION OF SAID CONCENTRATE, SAID FLOTATION AGENT AND SAID METAPHOSPHATE BEING RETAINED IN SAID SOLUTION AND THEREBY SEPARATED FROM SAID TREATED CONCENTRATED. 